.testBox_hairline {
  width: 100px;
  height: 100px;
  background-color: tan;
  border: 1px solid #f00;
  border-radius: 0;
}

@media (min-resolution: 2dppx) {
  .testBox_hairline {
    position: relative;
    border: none;
  }
  .testBox_hairline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 200%;
    height: 200%;
    border: 1px solid #f00;
    border-radius: 0;
    transform-origin: 0 0;
    transform: scale(0.5);
    box-sizing: border-box;
    pointer-events: none;
  }
}
